In a speech to mark the 35th anniversary of the 1979 revolution, he said American officials who claimed they did not want to see regime change in Iran were 'lying'.

He accused Washington of having a "controlling and meddlesome" attitude towards Iran.

America and Iran have had no official ties since 1980 when Iranian students occupied the US embassy in Tehran, taking 52 diplomats hostage.

Despite his apparent hostility, Mr Khamenei has given his guarded support to talks on Iran's nuclear programme being led by the new reformist government of President Hassan Rouhani and Foreign Minister Mohammad Javad Zarif.

The moves are seen as further signs that Iran is determined to exert its influence as an emerging regional economic and strategic power in the Middle East.